Coil to Globule Collapse Transitions of Polymers: The Effect of Adsorbed Surfactants

Recent experimental studies of the coil-to-globule transition of polymer chains in the presence of adsorbing anionic surfactants have shown a variety of novel transition curves. In this paper we theoretically model this system using a modified mean-field model. We show that as the surfactant concentration is increased, the transition becomes a strong first-order transition and occurs in the worse than θ regime. This is due to the adsorbed surfactants abruptly moving off the chain. We also implement a nonconstant density model in an attempt to understand the gradual collapse of these chains before the first-order transition.